Rotary kiln with integral cooler



March 12, 1957 N. s. BoRcH 2,785,115

ROTARY KILN WITH INTEGRAL COOLER Filed April 4, 1955 2 sheets-sheet 1 A Fill /M INV NTOR nd? fnd; mm2

March 12, 1957 N. s. BoRcl-l ROTARY KILN WITH INTEGRAL COOLER 2 Sheets-Sheet 2 Filed April 4, 1955 MMM ATTORNEY5 NVE ROTARY KEN WITH INTEGRAL COOLER Niels Soins Borch, Copenhagen, Denmark, assigner to F. L. Smidth & Co., New York, N. Y., a corporation of New Jersey Application April 4, 1955, Serial No. 499,171

Claims. (Cl. 202-95) This invention relates to rotary kilns and is concerned more particularly with a novel rotary kiln for the heating of materials in a non-oxidizing atmosphere followed by the cooling of the hot materials without exposure to the atmosphere. The rotary kiln of the invention may be utilized to especial advantage in the expulsion of volatile constituents from solid carbonaceous materials, such as Ianthracite and petroleum coke, in the practice of the method of my co-pending application, Ser. No. 216,836, led March 2l, 1951, now Patent No. 2,710,280, issued iune 7, 1955, of which this application is a continuation-in-part, and a form of the new kiln suitable for carrying out the method will be illustrated and described for purposes of explanation.

The method of the prior application involves advancing the solid carbonaceous material through the preheating section of an enclosure counter-current to volatiles, which have been expelled from material previously fed and are being burned by the admission of air to the preheating section. The material leaving the preheating section travels through a heating section of the enclosure, in which the material is heated by passage of an electric current therethrough, and volatiles remaining in the material are expelled and pass to the preheating section to be consumed therein. The material issuing from the heating section is then discharged.

The kiln of the present invention for use in practicing the method of the prior application is a tubular shell having a preheating section provided with means for supplying air thereto, a heating section with electrical heating means, a discharge section conducting the treated matei rial from the heating section, and a cooling section, in which the hot treated material is cooled out of contact with the air before being discharged. The material is cooled Without direct contact with the cooling medium and, when discharged, is at a temperature such that contact with the atmosphere will not cause combustion of any of the material.

For a better understanding of the invention, reference may be made to the accompanying drawings, in which Fig. l is a longitudinal sectional view of one form of the new kiln;

Fig. 2 is a longitudinal sectional View on an enlarged Scale of the cooling chamber and part of the discharge section of the kiln;

Fig. 3 is a sectional view on the line 3 3 of Fig. l;

Fig. 4 is a View similar to Fig. 2 showing a modified construction; and

Fig. 5 is a sectional View on the line 5-5 of Fig. 4.

The kiln installation shown in 1Eig. l comprises -a kiln made up of a preheating section 11, a heating section 12, a discharge section 13, `and a cooling chamber 14. The kiln is mounted for rotation in the usual way by means of circumferential tires 16a running on rollers 10b and is rotated by means of a driven pinion 19e, which meshes with a master gear 10d encircling the kiln, as is customary. The upper end of the kiln extends into a `nited States Patent ice smoke box 15, from which leads an exhaust pipe 16. The material to be treated is delivered by a conveyor 17 to a hopper 18 discharging through a rotary gate valve 19 and the material issuing from .the hopper travels along a sloping surface 20 through the smoke chamber to enter the upper end of the preheating section.

The hot material leaving the heating section 12 travels through the discharge section 13 and enters the cooling chamber 14. The preheating, heating, and discharge sections are provided with the usual refractory liner 25, but the cooling chamber is unlined. The lower end of the chamber is closed by an end plate 26, which has va cylindrical extension 27 projecting upwardly into the chamber concentrically therewith. The upper end of the extension is provided with a protective layer 27a and the extension carries lifter elements 2S at its outer surface, which extend to the inner surface or chamber 14, as illustrated, and rtend to cause the material to fill the annular space between the extension and the Wall of chamber 14. The material in the cooling chamber is cooled by water discharged upon the outside ofthe chamber through a nozzle pipe 29 and Water is also discharged upon the inside ot' the section 27 by a nozzle pipe 39 projecting into the lower open end of the section. The opening is defined by a hat ring 31 attached to the lower end of section 27 and is of less diameter than the ring, so that water is collected in the section by the ring. Excess Water may then be drained ont through the discharge pipe 32.

The preheating and discharge sections and the cooling chamber are or the same diameter, while the heating section 12 is of larger diameter and is provided with sets of electrodes 21, 22 extending through its opposite end Walls and angularly spaced about the section. The increased diameter of the heating section causes a bed of material to be maintained therein, which is of suiiicient depth to cover the electrodes at the bottomV of the section. The volatiles expelled from the material in the heating section travel up through the preheating section 11, where they are burned by air supplied through blowers 23 mounted on the wall of the section and having dis- Y charge pipes 23a, which project through openings into the section beyond the normal depth of the material traveling therethrough. A similar blower 24 may be mounted to supply air to the exhaust pipe 16 to bring about complete combustion of volatiles and any soot particles entrained thereby.

The lower end of the cooling chamber is encircled by a casing 33 divided into compartments 34 by radial walls 35. Openings 36 through the wall of chamber 14 lead into the respective compartments 34 at the trailing sides of walls 35 and a hinged door 37 is mounted on the wall of chamber 14 within each compartment adjacent the opening. The doors are so arranged that they open, as their openings approach the lowermost point in their travel, and then close, as the openings move upward during the rotation of the kiln. Each compartment has a discharge opening 38 adjacent the :trailing end of the `compartment and provided with a hinged door 39, which operates in the same Way as doors 37. A conveyor 4i) beneath the casing 33 receives the cooled material discharged from the casing.

In the operation of the kiln described, the raw carbonaceous material travels through the preheating zone 11 and enters the heating section 12 where the material is heated by the passage therethrough of van electric current. The volatiles expelled in section 12 travel upward through the preheating section where they are burned by air supplied by blowers 23. The material traveling through the preheating section is preheated in part by heat transferred from the volatiles and in part by heat generated by the combustion of the volatiles. Any unconsumed gases and solid particles entrained thereby are burned in the exhaust pipe 16 by air supplied by blower 24. The hot material leaving the heating section 12 passes through the discharge section 13 into the cooling chamber 14, where the material is advanced V'by the lifter elem-ents 28 to fill the annular space between the wall of the chamber and the cylindrical extensionl 27. The material in this space is cooled by water discharged upon the outside of the chamber Iand upon the inside of the cylindrical extension and the cooled material enters 'the compartments 34 successively. While material is entering a compartment through an opening 36, the discharge opening 38 from that compartment is closed by its door 39 and, When rthe material is leaving the compartment through the discharge Opening 38, the opening is closed by its door 37, This mode of operation of the doors insures that the hot material being cooled within chamber 14 will be kept from direct contact with the atmosphere. The cooled material issuingrthrough the discharge openings 38 of the compartments is deposited upon conveyor 40 and carried away.

The modified cooling chamber 14 shown in Figs. 4 and has many features in common with that above described and such features are identified by the same reference characters as are used in Figs. 1-3, incl, but with prime marks added. In order to increase the cooling eiect in the modiiied construction, the wall of the cooling chamber 14 is provided with outwardly extending longitudinal pockets 41 and these pockets are iilled With material as the kiln rotates and provides additional cooling surface, upon which water may be discharged through the nozzle pipe 29. Beyond the lower end of the pockets, the cooling chamber is provided with a discharge casing 33 similar in construction and operation to that employed with charnber 14.

I claim: Y

1. A rotary kiln for heat treatment of material ina substantially non-oxidizing atmosphere'followed by cooling of thertreated material out of contact with the outside air, which comprises a tubular shell having a plurality of encircling tires, means engaging the tires and supporting the kiln for rotation at a low angle to the horizontal, means for rotating the kiln; a closure plate secured to and closing the lower end of the shell and having a tubular section of less diameter than the shell extending upwardly into the shell concentrically therewith, the shell having a plurality of angularly spaced discharge openings adjacent the closure plate, and a casing mounted on the shell to enclose the zone of the shell with the discharge openings and having means for discharging material entering the casing through VVthe, openings, as the shell is rotated.

2. The rotary kiln of claim l, in which means are provided for discharging a cooling medium upon the inner surface of the tubular section of the closure plate and upon the outer surface of the section of the shell enclosing the tubular section of the closure plate.

3. The rotary kiln of claim l, in which lifting members are mounted on the outside of thetubular section of the closure plate and extend to the inner surface of the shell, the members being formed to maintain the annular space between the tubular section and the shell full of the material.

4. The rotary kiln of claim 1, which includesk a preheating section, a heating section, Va discharge section,` and a cooling section disposed ini the order stated, the heating section having electrical means for heating material therein to expel volatile gaseous products therefrom and the preheating section having means for supplying air thereto for combustion or" the volatiles therein,'and the closure plate closes the end ofthe cooling section.

5. The rotary kiln of claim l, in which the casing is Y subdivided into a plurality of compartments into which the respective discharge openings through thev shell lead, each compartment has a discharge opening angularly spaced from the discharge opening through the shell leading into the compartment, and all the discharge openings are provided with hinged doors swinging open vas thel doors approach their lowermost positions during the rotation of the shell and swinging shut -as the Ydoors move upward duringV such rotation.

References Cited in the Vtile of this patentY A UNITED STATES PATENTS 1,5 47,33 l 

1. A ROTARY KLIN FOR HEAT TREATMENT OF MATERIAL IN A SUBSTANTIALLY NON-OXIDIZING ATMOSPHERE FOLLOWING BY COOLING OF THE TREATED MATERIAL OUT OF CONTACT WITH THE OUTSIDE AIR, WHICH COMPRISES A TUBULAR SHELL HAVING A PLURALITY OF ENCIRCLING TIRES, MEANS ENGAGING THE TIRES AND SUPPORTING THE KILN FOR ROTATION AT A LOW ANGLE TO THE HORIZONTAL, MEANS FOR ROTATION AT A LOW ANGLE TO THE HORITO AND CLOSING THE LOWER END OF THE SHELL AND HAVING A TUBULAR SECTION OF LESS DIAMETER THAN THE SHELL EXTENDING UPWARDLY INTO THE SHELL CONCENTRICALLY THEREWITH, THE SHELL HAVING A PLURALITY OF ANGULARLY SPACED DISCHARGE OPENINGS ADJACENT THE CLOSURE PLATE, AND A CASING MOUNTED ON THE SHELL TO ENCLOSE THE ZONE OF THE SHELL WITH THE DISCHARGE OPENINGS AND HAVING MEANS FOR DISCHARGING MATERIAL ENTERING THE CASING THROUGH THE OPENINGS, AS THE SHELL IS ROTATED. 